Endoscopic stapling devices and methods

ABSTRACT

Described herein are endoscopic staplers used to apply one or more fasteners to body tissue. In one embodiment, a fastener-applying device, which is preferably a stapler, is passed transorally into the stomach and used to plicate stomach tissue by engaging tissue from inside of the stomach and drawing it inwardly. In the disclosed embodiments, the tissue is drawn inwardly into a vacuum chamber, causing sections of serosal tissue on the exterior of the stomach to be positioned facing one another. The disclosed staplers allow the opposed sections of tissue to be moved into contact with one another, and preferably deliver staples for maintaining contact between the tissue sections at least until serosal bonds form between them. Each of these steps may be performed wholly from the inside of the stomach and thus can eliminate the need for any surgical or laparoscopic intervention. After one or more plications are formed, medical devices may optionally be coupled to the plication(s) for retention within the stomach.

FIELD OF THE INVENTION

The present invention relates generally to the field of systems andmethods for performing endoscopic surgery, and specifically to systemsand methods for endoscopic stapling of tissue within body cavities.

BACKGROUND OF THE INVENTION

An anatomical view of a human stomach S and associated features is shownin FIG. 1A. The esophagus E delivers food from the mouth to the proximalportion of the stomach S. The z-line or gastro-esophageal junction Z isthe irregularly-shaped border between the thin tissue of the esophagusand the thicker tissue of the stomach wall. The gastro-esophagealjunction region G is the region encompassing the distal portion of theesophagus E, the z-line, and the proximal portion of the stomach S.

Stomach S includes a fundus F at its proximal end and an antrum A at itsdistal end. Antrum A feeds into the pylorus P which attaches to theduodenum D, the proximal region of the small intestine. Within thepylorus P is a sphincter that prevents backflow of food from theduodenum D into the stomach. The middle region of the small intestine,positioned distally of the duodenum D, is the jejunum J.

FIG. 1B illustrates the tissue layers forming the stomach wall. Theoutermost layer is the serosal layer or “serosa” S and the innermostlayer, lining the stomach interior, is the mucosal layer or “mucosa”MUC. The submucosa SM and the multi-layer muscularis M lie between themucosa and the serosa.

There are a number of applications for endoscopic application offasteners such as staples to tissue within a body cavity. Some of thoseapplications involve forming tissue structures such as plications orfolds in tissue of the body cavity.

Several prior applications, including International Application No. WO2005/037152 having an international filing date of Oct. 8, 2004 and U.S.application Ser. No. 11/439,461, filed May 23, 2006 (both incorporatedherein by reference) describe methods according to which medicalimplants are coupled to tissue structures formed within the stomach.According to these applications, devices for inducing weight loss (e.g.by restricting and/or obstructing flow of food into the stomach, and/orby occupying a portion of the stomach volume) may be coupled to tissuetunnels or plications formed from stomach tissue.

For example, U.S. application Ser. No. 11/439,461 describes arestrictive and/or obstructive implant system for inducing weight loss.In one embodiment, flexible loops are coupled to tissue plicationsformed in the gastroesophageal junction region of the stomach. Animplant, such as a flow restrictive and/or obstructive implant, ispassed through the loops 2 and thus retained in the stomach.

In other instances, tissue plications may themselves be sufficient toprovide the necessary treatment. For example, the plications may be usedto reduce stomach volume or form a flow restriction within the stomachas disclosed in WO 2005/037152 and in Applicants' co-pending applicationSer. No. 11/542,457, filed Oct. 3, 2006, U.S. Publication No.2007-0219571, which is incorporated herein by reference.

Other types of implants may be coupled to such plications or othertissue structures for a variety of purposes. These implants include, butare not limited to prosthetic valves for the treatment ofgastro-esophageal reflux disease, gastric stimulators, pH monitors anddrug eluting devices that release drugs, biologics or cells into thestomach or elsewhere in the GI tract. Such drug eluting devices mightinclude those which release leptin (a hormone which creates feelings ofsatiety), Ghrelin (a hormone which creates feelings of hunger),octreotide (which reduces Ghrelin levels and thus reduces hunger),Insulin, chemotherapeutic agents, natural biologics (e.g. growth factor,cytokines) which aid in post surgery trauma, ulcers, lacerations etc.Still other implants might be of a type which might provide a platformto which specific cell types can adhere, grow and providebiologically-active gene products to the GI tract, and/or a platform forradiation sources that can provide a local source of radiation fortherapeutic purposes, or provide a platform whereby diagnostic ligandsare immobilized and used to sample the GI tract for evidence of specificnormal or pathological conditions, or provide an anchor point forimaging the GI tract via cameras and other image collecting devices.

The prior applications listed above, address the desirability of formingtissue plications, pockets or tunnels in a way that regions of serosaltissue (i.e. the tissue on the exterior surface of the stomach) areretained in contact with one another. Over time, adhesions formedbetween the opposed serosal layers create strong bonds that canfacilitate retention of the plication/pocket/tissue over extendeddurations, despite the forces imparted on them by stomach movement andimplanted devices.

Regardless of the application for which a plication is being formed, itis highly desirable to form that plication using steps carried out fromwithin the stomach using instruments passed down the esophagus, ratherthan using more invasive surgical or laparoscopic methods. The presentapplication describes endoscopic staplers which may be passedtransorally into the stomach and used to form serosal-to-serosalplications in a stomach wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic illustration of a human stomach and a portion ofthe small intestine.

FIG. 1B is a cross-sectional perspective view of a portion of a stomachwall, illustrating the layers of tissue forming the wall.

FIG. 2 illustrates an endoscopic stapling system.

FIGS. 3A-3C are perspective views showing the stapler head of thestapling system of FIG. 2 in three different positions.

FIG. 4 is a perspective view of the stapler head, with the membraneremoved.

FIG. 5 is a perspective view of the proximal end of the staple housingof the stapler head of FIG. 4.

FIG. 6 is a perspective view of the distal end of the staple housing ofthe stapler head of FIG. 4.

FIG. 7 is an exploded perspective view showing elements advanceablewithin the staple housing during compression and stapling operations.

FIG. 8 is a plan view of a staple reinforcement device.

FIG. 9 is a side elevation view of a staple cartridge.

FIG. 10 is a perspective view of the staple housing similar to FIG. 6,but showing some of the elements of FIG. 7 within the housing.

FIGS. 11A-11D are a series of schematic representations of the hydraulicchamber and pistons, illustrating operation of an exemplary hydraulicsystem during tissue compression and stapling.

FIG. 11E is similar to FIG. 11D and shows an alternative pistonconfiguration.

FIG. 12 is a perspective view of the anvil housing of the stapler headof FIG. 4.

FIG. 13 is a perspective view of the anvil support.

FIG. 14 is a plan view of the anvil.

FIG. 15A is a cross-sectional side view of the cutting device and afirst embodiment of a cutting board.

FIG. 15B is a cross-sectional side view of the cutting device and asecond embodiment of a cutting board.

FIG. 16 is a perspective view of the hinged arm assemblies of thestapler head of FIG. 4.

FIG. 17 is a top plan view of the stapler head of FIG. 4 in thestreamlined position for introduction into the body. Both the membraneand the membrane raiser are not shown for purposes of clarity.

FIG. 18 is similar to FIG. 17 and illustrates hidden features of FIG.17.

FIG. 19 is a perspective view of the stapler head in an intermediate,partially expanded, position.

FIG. 20 is a plan view similar to FIG. 17 but showing the stapler headin the intermediate position.

FIG. 21 is similar to FIG. 20 and illustrates hidden features of FIG.20.

FIG. 22 is a perspective view of the stapler head in a fully expanded,full compression position.

FIG. 23 is a plan view similar to FIG. 20 but showing the stapler headin the full compression position.

FIG. 24 is similar to FIG. 23 and illustrates hidden features of FIG.24.

FIGS. 25A-25B are perspective views showing the staple housing,cartridge and a portion of the membrane raiser. These figures illustratethe steps of detaching a staple cartridge from the staple housing.

FIG. 26 is a perspective view of the stapler of FIG. 2, with the staplehead removed.

FIG. 27A is a plan view of the articulating section of the stapler ofFIG. 2, showing the drive fluid lines.

FIG. 27B shows a drive fluid line having an alternate longitudinallyexpandable shape.

FIG. 28 is a cross-sectional side view of the handle of the stapler ofFIG. 2.

FIG. 29 is a perspective view of the handle of the stapler of FIG. 2.

FIGS. 30A and 30B are plan views of the proximal face of the staplehousing, showing a method for attaching the end plate of the staplerhandle to the staple housing.

FIGS. 31A-31E are a series of drawings schematically illustrating use ofthe system of FIG. 2 to form a plication in a stomach.

FIGS. 32A-32C are a series of perspective views illustrating use of thestapler of FIG. 2 to acquire, compress, and then staple stomach walltissue to form a plication in the stomach. The membrane is not shown inthese drawings.

FIG. 33 is a top plan view of a plication formed in body tissue.

FIGS. 34 and 35 are perspective views of an alternative stapler headequipped to carry additional tools.

DETAILED DESCRIPTION OF THE DRAWINGS

The present application describes endoscopic fastener-applying deviceswhich in preferred embodiments may be passed transorally into thestomach and used to plicate stomach tissue.

In the disclosed embodiments, tissue is drawn inwardly into a vacuumchamber, although tissue may be drawn inwardly using other components(e.g. graspers) that do not involve the use of a vacuum. When a portionthe interior stomach wall is drawn inwardly, sections of serosal tissueon the exterior of the stomach are positioned facing one another. Thedisclosed fastener applying device allows the opposed sections of tissueto be moved into contact with one another, and delivers fasteners thatwill hold the tissue sections together until at least such time asserosal bonds form between them. Each of these steps may be performedwholly from the inside of the stomach and thus can eliminate the needfor any surgical or laparoscopic intervention. After one or moreplications is formed, medical devices (including, but not limited to anyof the types listed above) may be coupled to the plication(s) forretention within the stomach.

The disclosed embodiments include an optional feature that forms a holeor cut in a plication using the fastener-applying device. This hole orcut might be formed so that a portion of a medical implant may be passedthrough or linked to the hole/cut, or it may be formed so as to provokea healing response that will contribute to the strength of the resultingtissue bond.

In the description of the embodiments given below, the fastener-applyingdevices are described as being staplers, and exemplary methods are givenwith respect to the formation of plications in stomach tissue. It shouldbe understood, however, that the embodiments described herein includefeatures having equal applicability for applying other types offasteners, and for applying staples or other fasteners for purposesother than formation of plications. The disclosed embodiments andmethods will also find use in parts of the body outside the GI system.Additionally, although the disclosed embodiment features circularstapling and cutting of a concentric hole, modifications are conceivablein which linear stapling can be accomplished, as well as circular orlinear stapling without cutting.

FIG. 2 illustrates one embodiment of a system 10 for tissue staplingthat is suitable for endoscopic use, as well as surgical or laparoscopicuse if desired.

Generally speaking, system 10 includes a stapler 12 having a staplerhead 14 positioned on a distal portion of a shaft 16. A handle 18 on theshaft 16 controls articulation of the stapler head 14 and actuation ofthe tissue acquisition, tissue compression, and stapling functions ofthe stapler head 14. Vacuum and fluid sources 20, 25 are fluidly coupledto the handle 18 for use in tissue acquisition, compression and staplingas discussed below. The vacuum source 20 may be the “house vacuum”accessible through a coupling on the wall of the operating room, or anauxiliary suction pump. The stapler may include a switch 21 allowing theuser to control airflow between the vacuum source and stapler.

The fluid source 25 may be a single source of drive fluid (e.g. water,saline, oil, gas) or multiple sources, but in each case the fluid sourcepreferably includes two actuators separately used to control flow intoeach of two hydraulic lines (one for tissue compression and one forstapling). An endoscope 22 insertable through a lumen in the shaft 16permits visualization of the plication procedure. The system mayoptionally include an overtube, such an endoscopic guide tube 23, havinga lumen for receiving the stapler 12.

Referring to FIG. 3A, a covering or membrane 24 encloses the staplerhead 14 to form a vacuum chamber within the stapler head 14. The sideexposed to the tissue to be plicated remains uncovered by the membrane24 to allow tissue to be drawn into the chamber during use. For example,the membrane 24 may include a side opening 26 as shown in FIG. 3B.Membrane 24 is preferably formed of silicone, elastomeric material, orany other inelastic or elastic flexible or deformable biocompatiblematerial capable of forming a vacuum chamber that will expand in volumeto accommodate tissue drawn into the chamber.

At least a portion of the membrane is at least partially transparent. Inbeing at least partially transparent, the membrane is formed of amaterial, or includes sections of material, that will allow the user tosee through the membrane well enough to confirm (via endoscopicobservation) that an appropriate volume of tissue has been acquired intothe stapler head prior to staple application. The opening 26 may besurrounded by a reinforced section 27 formed of material that willstrengthen the area around the opening 26. Reinforced section 27 may beformed of a thicker section of the membrane material, and/or a higherdurometer material. Alternatively, reinforcing ribs or other structuresor elements may be formed into or onto the membrane material, orembedded in the membrane material.

Stapler Head

The stapler head 14 is designed to have a minimum profile duringinsertion to the plication site, and to then transform into a muchlarger profile device having a large internal volume. For example, inone embodiment the vacuum chamber might have an initial internal volumeof 0.2 cubic inches, and an expanded volume of 0.6 cubic inches (i.e.the internal chamber volume after subtracting the volume occupied by thestapler head components positioned within the vacuum chamber). Thislarge internal volume allows a large volume of tissue to be drawn intothe vacuum chamber and stapled. In this way, the stapler head creates alarge plication without requiring invasive techniques for insertion. Theunique features of the stapler head allow in situ volumetric expansionof the stapler head using a minimum of motion and force input.

Features of the stapler head are shown in FIGS. 4-10. For clarity, themembrane is not shown in these figures. Referring to FIG. 4, staplerhead 14 generally includes a first member comprising a proximal staplehousing 28, a second member comprising a distal anvil housing 30, and atleast one elongate member but preferably a pair of hinged arm assemblies32.

The staple housing and anvil housing are arranged to allow tissue to becompressed between contact surfaces on each of the staple housing andthe anvil housing. In the disclosed embodiment, the contact surfaces areon a staple holding portion of the staple housing and an anvil on theanvil housing.

The arm assemblies 32 extend between the staple housing 28 and anvilhousing 30 on opposite sides of the stapler head 14. Proximal and distalpins 34, 36 pivotally couple each arm assembly 32 to the staple housing28 and the anvil housing 30. An expansion member comprising a membraneraiser 37 also extends between the staple housing 28 and the anvilhousing 30. Although the membrane 24 is not shown in FIG. 4, it shouldbe understood that the membrane raiser 37 is positioned opposite theopening 26 (FIG. 3B) in the membrane. In the illustrated embodiment,membrane raiser 37 includes a link 38 pivotally mounted to the staplehousing by a pin 42, a corresponding link 40 pivotally mounted to theanvil housing by pin 44, and spring wires 46 coupling the links 38, 40to one another.

Staple Housing

Turning to a more detailed discussion of the stapler head components,the staple housing 28 can be seen separated from other components inFIGS. 5 and 6. As shown in FIG. 5, proximal face 48 of the staplehousing includes input ports 50 a, 50 b through which fluid is directedfor hydraulic actuation of the tissue compression, stapling, andoptional cutting operations of the stapler head. Seals 51 surround theports 50 a, 50 b to minimize fluid leakage.

Vacuum ports 52 are fluidly coupled to a vacuum source 20 (FIG. 2) thatis selectively activated to create negative pressure in the vacuumchamber for tissue acquisition. The vacuum ports 52 are connected to thevacuum source 20 by flexible tubing (not shown) in the stapler shaft 16(FIG. 2). Mounting holes 54 are used to mount the stapler head 14 to theshaft 16.

The staple housing 28 includes upper and lower sections 58 a, 58 b aboveand below open side sections 56. The upper section 58 a includes arecess 60 within which the pivot pin 42 for link 38 (FIG. 4) is mounted.As best shown in FIG. 6, bores 62 are positioned in the upper and lowersections 58 a, 58 b to receive pins 34 (FIG. 4) that serve as theproximal pivot points for arm assemblies 32. Guide slots 64 extendlongitudinally through the upper and lower sections 58 a, 58 b.

Referring to FIG. 6, a hydraulic chamber 66 is disposed within thestaple housing 28. Within the hydraulic chamber 66 (FIG. 6) is adedicated hydraulic circuit for driving the tissue compression andstapling functions of the stapler. Chamber 66 is fluidly coupled to thefluid input ports 50 a, 50 b (FIG. 5). As will be discussed in detail inconnection with FIGS. 11A-11D, fluid driven into the hydraulic chamber66 via input ports 50 a, 50 b sequentially advances a system ofhydraulic pistons (not shown) that act on other components to compressthe tissue, and that drive the staples and cutting element through thecompressed tissue.

FIG. 7 illustrates components of the stapler head that are driven by thehydraulic system for compression, stapling, and cutting. For clarity,these components are shown separated from the staple housing and fromeach other. In this discussion, the components that are driven by thehydraulic system will be described. The hydraulic system itself isdescribed in a later section in connection with FIGS. 11A-11D.

In particular, FIG. 7 illustrates a drive member which takes the form ofa disk 68 in the staple housing. In the assembled housing, disk 68 ispositioned such that it will be pushed distally by a hydrauliccompression piston (not shown). The drive member is coupled to the armassemblies 32, anvil housing, and staple housing so that advancing thedrive member distally effects tissue compression by bringing the contactsurfaces of the staple housing and anvil housing relatively towards oneanother.

Disk 68 includes mounting bores 70, a central opening 72, and alignmentposts 74. Referring briefly to FIG. 10, in the assembled stapler head,disk 68 is coupled to the stapler housing 28 using pins 84 that extendthrough the housing's guide slots 64 and through mounting bores 70 inthe disk 68.

A portion of the staple housing 28 contains staples to be fired into thetissue. The staples are contained within a staple holder on the staplehousing. The staple holder may have a number of differentconfigurations. For example, it may be an integral portion of the staplehousing, or a separate part mounted or attached to the staple housing,and/or it may be moveable relative to the body of the staple housing toeffect tissue compression prior to stapling. In any of these examples,the staple holder may be a removable/replaceable cartridge, and/or itmay be refillable by inserting additional staples into it. In otherembodiments, the staple holder may be neither replaceable norrefillable.

In the disclosed embodiment, the staple holder is a removable staplecartridge 78 that can be replaced with another cartridge after staplefiling. In this embodiment, the staple cartridge is moveable relative tothe body of the staple housing to compress the tissue prior to staplefiring.

Referring again to FIG. 7, staple cartridge 78 is positionable withinthe staple housing, distal to the disk 68, such that distal advancementof the disk by the compression piston pushes the cartridge distally tocompress tissue disposed between the cartridge and anvil. Grooves 79 onthe exterior of the cartridge slide over corresponding ones of thealignment posts 74 during insertion of the cartridge into the staplerhead. FIG. 10 shows the alignment posts prior to loading of a cartridgeinto the staple housing. As shown, the alignment posts 74 may havetapered ends to facilitate loading of the cartridge over the posts.

Again referring to FIG. 7, cartridge 78 includes a number of staplelocations 80, each housing a staple. The staple cartridge is equippedwith bosses 81 to retain a staple line reinforcement device 83 of thetype shown in FIG. 8 and disclosed in detail in commonly-owned U.S.application Ser. No. 11/542,457, entitled ENDOSCOPIC APPLICATION DEVICESAND METHODS, filed Oct. 3, 2006, and published Sep. 20, 2007 as US2007-0219571. To summarize briefly, this type of reinforcement device 83may be a ring or other element positionable against the distal face ofthe staple cartridge. When the ring is placed on the cartridge, openings85 in the ring align with prongs of some of the staples in thecartridge. When staples are driven from the cartridge, these prongs passthrough associated ones of the openings 85 and capture the ring 83against the adjacent body tissue.

Referring to FIGS. 7 and 9, a number of undercut bosses 81 on theanvil-facing side of the cartridge may be used to lock the reinforcementdevice 83 in place on the face of the staple cartridge. Other positiveshapes, such as mushrooms, hooks, and tilted bosses could be used toaccomplish the same end. Negative shapes, such as pockets or groovesformed into the surface of the cartridge, may also be employed to engagecorresponding features on the reinforcement device 83. As anotheralternative, the reinforcement device may be held in place on thecartridge using adhesives.

A cutter element 86 extends through the central opening 72 (FIG. 7) ofthe disk 68. The cutter element is shown as a tubular punch having asharpened wall and a lumen 87, but may be provided in alternative forms.A staple pusher 76 is mounted to the cutter element, distally of thedisk as can be seen in the assembled view of FIG. 10. Staple pusher 76includes pusher elements 82 proportioned to slide into the cartridge'sstaple locations 80 as the staple pusher 76 is advanced into the staplecartridge 78, thus driving the staples from the cartridge. Ahydraulically-driven staple piston (not shown in FIG. 7) in thehydraulic chamber 66 is coupled to the cutter element 86 such thatadvancement of the stapler piston advances the staple pusher 76 andcutter element 86 in a distal direction.

Fluid Drive System

The fluid drive system used to actuate compression, stapling and cuttingmay be configured in various ways. The following paragraphs describe oneexemplary configuration for the fluid drive system, which in thisembodiment is a hydraulic system. FIGS. 11A and 11B schematically showthe fluid flow in the hydraulic chamber 66 of the staple housing 28during both compression and stapling stages of actuation. Referring toFIG. 11A, compression piston 106 is disposed within hydraulic chamber66. Disk 68 (also shown in FIGS. 7 and 10) is positioned in contact withor slightly distal to piston 106. Compression piston 106 is generallycup-shaped, having a rear wall 108 and a side wall 110 enclosing aninterior 111. O-ring seals 112 are spaced-apart on a proximal portion ofthe side wall 110. Channels 114 are formed through the side wall 110,between the o-ring seals 112.

A second piston, referred to as the staple piston 116, is positioned inthe interior 111 of compression piston 106, against the rear wall 108.Although not shown in FIGS. 11A-11D, cutting element 86 (FIG. 7), withthe staple pusher 76 thereon, is positioned in contact with or slightlydistal to the staple piston 116. An o-ring seal 118 surrounds a portionof the staple piston 116 that is distal to the channels 114 in thecompression piston.

A first fluid channel 120 extends from fluid port 50 a in the staplerhousing 28 to a proximal section of the hydraulic chamber 66. A secondfluid channel 122 extends from fluid port 50 b in the stapler housing toa more distal section of the hydraulic chamber 66. Fluid flow from port50 a and fluid channel 120 against the compression piston cylinder isshown in FIG. 11A. Fluid pressure within the hydraulic chamber 66advances the compression piston 106, with the stapler piston 116 withinin it, in a distal direction. FIG. 11B shows the compression piston 106approaching the end of its travel. Once the compression piston reachesthe end of its travel as shown in FIG. 11C, channel 114 in thecompression piston 106 aligns with channel 122 in the housing, allowingfluid introduced through fluid port 50 b to enter the interior of thecompression piston 106 via channel 122. The fluid entering the interiorof the compression piston drives the staple piston distally as shown inFIG. 11D. In an alternative embodiment shown in FIG. 11E, a third piston117 is provided for separately driving the cutting element 86. In thisembodiment, fluid introduced into a third drive fluid port 50 c causesadvancement of the third piston 117. The pistons 106, 116 and 117 andassociated fluid paths may be arranged so that fluid cannot enter theinterior of the stapler piston to advance the cutting piston 117 untilcompression piston 106 has traveled to the tissue-compression positionand stapler piston 116 has in turn traveled to the stapling position.

The anvil housing (identified by numeral 30 in FIG. 4) will next bedescribed with reference to FIG. 12. The anvil housing 30 includesmounting bores 88 for receiving pivot pins 36 at the distal end of thehinged arm assemblies 32. The upper section of the anvil housing 30includes a section 94 through which the pivot pin 44 for link 40 (FIG.4) is mounted.

A central bore 90 extends longitudinally through the anvil housing 30.An anvil support 92 is longitudinally slidable within the bore. Both thebore 90 and the anvil support 92 are preferably formed to havenon-circular cross-sections (such as the illustrated rectangularcross-section) with flat bearing surfaces to prevent rotation of thepiston within the bore.

FIG. 13 shows the anvil support 92 separated from the anvil housing 30.The distal portion of the anvil support 92 is split into upper and lowerplates 95 a, b. Plate 95 a has a bore 93 axially aligned with a similarbore in plate 95 b. The proximal portion of the anvil support 92 carriesthe anvil 96. As shown in FIG. 14, anvil 96 includes a plurality ofindentations 98 positioned such when staples are driven from the staplecartridge, each staple leg engages one of the indentations, which causesthe staple leg to fold. A central opening 97 extends through the anvil96 and is contiguous with a lumen in the anvil support 92.

The anvil 96 and the staple cartridge 78 (FIG. 7) are the two parts ofthe stapler head which exert force on the tissue to be stapled. As shownin FIGS. 9 and 14, the preferred anvil and cartridge are designed to usea minimal amount of material surrounding the indentations 98 of theanvil 96 and the staple locations 80 of the cartridge 78—so that theamount of anvil/cartridge surface area contacting the tissue is as smallas possible. When subjected to a constant force, a smaller footprintwill damage less tissue than would a larger footprint, since a smallerarea of tissue is squeezed between the anvil and cartridge. However, thetissue that does get squeezed experiences more pressure from the givenforce because the force is distributed over a smaller area. In otherwords, the minimized footprint creates more pressure on the tissue withless force. This is advantageous from a mechanical standpoint becausethe stapler head need not supply or withstand as much force as would beneeded with a larger-footprint cartridge and anvil.

Referring to FIG. 7, in the illustrated embodiments, the staplecartridge 78 has an outer wall that tracks the contours of the stapleshoused within it, thus forming a number of pedals 73 surrounding theouter staple positions or slots 80 a, with the grooves 79 disposedbetween the pedals, adjacent to the inner staple positions 80 b. Ratherthan providing each staple position to be fully surrounded by cartridgematerial, the staple positions 80 a, 80 b preferably each include a backwall 71 a and a retaining element attached to the wall and positioned toretain a staple between the retaining element and the back wall. In FIG.7, the retaining element comprises a pair of wings 71 b that curveinwardly from the back wall 71 to define a slot that is sufficientlybounded to retain a staple within the staple position, but that ispreferably not bounded around its full circumference. The anvil has asimilar pedal arrangement, as shown in FIG. 13.

Referring again to FIG. 13, a plate 99 is positioned on the anvil 96such that the distally-advancing cutting element 86 will advance intocontact with the plate 99 during tissue cutting. In one embodiment, theplate 99 may be seated within the opening 97 in the anvil. The plate 99,which will also be referred to as the “cutting board”, has a hole 101 init which relieves the pressure of the captured tissue and preventshydraulic locking, a condition in which the punch and plate create aclosed volume. If it is desired to move the cutting element 86 aftercontact is made, pressure will increase inside this closed volume and itwill resist further motion. This may prevent or adversely affect tissuecutting.

The cutting board is preferably designed so as to not serve as a hardstop against advancement of the cutting element 86. If the cuttingelement 86 is stopped by the cutting board, the stapling piston willalso be stopped and incomplete staple formation may result. Therefore,it is preferred that the cutting element 86 is allowed to penetrate ordisplace the cutting board during and after the tissue is cut.

FIGS. 15A and 15B illustrate the cutting element 86 advanced intocontact with two different embodiments of cutting boards. In the FIG.15A embodiment, the material of cutting board 99 a is a relatively softmaterial, such as an elastomeric silicone, which is cut by the advancingcutting element as shown. This material allows the sharp distal end ofthe cutting element to move into the cutting board during the finalstage of staple formation. In the FIG. 15B embodiment, the cutting board99 b can be made of a harder material positioned with a compressibleobject such as an elastomeric spring 99 c behind it. In the figure, thisspring is an o-ring. Advancement of the cutting element 86 against thecutting board 99 b causes the cutting board to be displaced distallyagainst the spring 99 c. The advancing cutting element 86 experiencesincreasing resistance as the o-ring is compressed. Other spring shapesand materials, such as coiled wire, spring washers and leaf springs canbe used to achieve the same result. The chamfer 99 d on the surface ofthe cutting board 99 b may help to align the cutting element 86 as it isforced into contact with the cutting board.

Arm Assemblies

Following is a discussion of the features of the arm assemblies 32. FIG.16 shows the arm assemblies 32 separated from the other elements of thestapler head. In general, each arm assembly has a first arm sectionpivotally coupled to the staple housing and a second arm sectionpivotally coupled between the first arm section and the anvil housing.While not present in the illustrated embodiment, additional arm sectionsmay be positioned between the first and second arm sections.

Each arm assembly includes a proximal arm 100 and a distal arm 102joined to one another to form a hinge 104. Each of the proximal arms 100has a longitudinal cutout 108 and a spreader arm 110 pivotally mountedwithin the cutout 108. The distal end of each spreader arm 110 includesa bore 112. Pin 84 is positioned within the bore 112. As disclosed inconnection with FIG. 10, this pin 84 extends through the disk 68 and hasends that ride within the slots 64 (FIG. 6) on the lower and uppersections of the stapler housing. Longitudinal movement of the disk 68within the stapler housing will thus advance the pins 84 within theircorresponding slots 64, causing the spreader arms 110 to pivot relativeto the pins 84 and to thus drive the arm assemblies 32 outwardly.Additional specifics concerning movement of the arm assemblies 32 is setforth in the section entitled Stapler Head Operation.

Distal arms 102 of the arm assemblies include pins 36 which, asdiscussed, are pivotally mounted to the anvil housing 30 (FIG. 4). Apair of drive links 114 are provided, each of which has a first endpivotally attached to a corresponding one the distal arms 102 and asecond end pivotally coupled to a common pin 116. In the assembledstapler head, pin 116 is positioned in the bores 93 of the upper andlower plates 95 a, 95 b of the anvil support (see plates 95 a, b in FIG.12). As detailed in the Stapler Head Operation section below, when thespreader arms 110 drove the arm assemblies 32 outwardly, drive links 114act on the pin 116 to push the anvil support in a proximal direction,causing the anvil to advance proximally towards the staple cartridge.

Stapler Head Operation

The following discussion centers on the manner in which the armassemblies function to expand the vacuum chamber and to compress tissuethat has been drawn into the chamber using suction. As an initial steppreceding chamber expansion, the stapler head is positioned with theopening 26 in the membrane 24 in contact with tissue at the location atwhich plication creation is desired. Vacuum source 20 (FIG. 2) isactivated to apply vacuum to the inside of the vacuum chamber defined bythe membrane. Tissue in contact with the opening 26 (FIG. 3B) will bedrawn into the vacuum chamber between the staple housing 28 and theanvil housing 30. After the tissue is drawn in, the stapler profile ischanged, expanding the volume of the chamber within the membrane.

The streamlined position of the stapler head 28 prior to expansion isshown in FIGS. 4, 17 and 18. In particular, the hinged arm assemblies 32and membrane raisers 37 are in generally straight orientations. Theproximal arms 100 serve as the drive arms for chamber expansion andtissue compression. Motion of these arms is initiated when water underpressure is forced into the hydraulic circuit of the staple housing.Referring to FIG. 19, the fluid pressure advances disk 68 (by action ofthe compression piston 106, not shown in FIG. 19). Disk 68 in turnpushes the staple cartridge 78 toward the anvil 96 as shown in FIGS.19-21, causing the staple cartridge 78 to extend further from the staplehousing 28.

Both the disk 68 and the arm spreaders 110 are coupled to the pins 84.For this reason, the longitudinal movement of the disk 68 within thestapler housing 28 will carry the pins 84 distally within theircorresponding slots 64. The arm spreaders 110 will consequently pivotrelative to the pins 84, driving the proximal arms 100 outwardly.Outward movement of proximal arms 100 at hinge 104 causes the distalarms 102 to also pivot outwardly at hinge 104, forming an angle betweenthe proximal and distal arms 100, 102. Naturally, formation of the anglebetween the arms 100, 102 shortens the effective length between theremote ends of the arms, causing the distal pins 36 of the distal arms102 to carry the anvil housing 30 towards the staple cartridge. Thepivoting movement of the distal arms 102 further causes drive links 114to act on pin 116 to push the anvil support in a proximal direction.This moves the anvil support relative to the anvil housing in a proximaldirection at the same time the anvil housing is also moving proximally.

In essence, one motion, that of the hydraulically driven compressionpiston, creates at least three motions, illustrated by arrows A1, A2 andA3 in FIGS. 19-21. These three motions include: the staple cartridge 78moving relative to the staple housing in a direction towards the anvil96 (arrow A1), the anvil housing 30 moving toward the staple housing 28(arrow A2) and the anvil 96 itself moving relative to the anvil housing30 in a direction towards the cartridge (arrow A3). This compound motionof the anvil toward the staple cartridge enables a small displacement ofthe compression piston to quickly compress tissue in the grip ofstapler. The multiplication of motion also enhances force transmissionbetween the two housings by keeping the angle at hinge 104, between theproximal (driven) arm and the distal (drive) arm, as large as possible.

The relative motion of the two housings 28, 30 toward each other alsodrives upward links 38, 40 and their interconnecting spring wires 46 onthe top of the stapler head 14. Together, the links and spring wiresraise the top of the membrane, creating more volume to accommodateexpansion of the tissue during compression.

Compression of the tissue is halted when the pins 84 traveling in slots64 in the staple housing 28 reach the limit of travel, as shown in FIGS.22-24. Thus, the slots and associated components are dimensioned to setthe desired separation distance between the tissue contact surfaces onthe stapler side and the anvil side of the stapler head. Exemplaryseparation distances for use in stomach wall plications might includeapproximately 0.06-0.07 inches (e.g. for use with staples having legs of5.5 mm length) or 0.109 inches for 6.5 mm leg length staples.Application of additional pressure into the hydraulic circuit will notcompress the tissue any further.

Moreover, because of the piston arrangement, the stapling function iseffectively locked out until tissue compression is complete. With thisarrangement, fluid introduced via the fluid port 50 b (FIG. 11A) intothe staple fluid channel 122 prior to completion of tissue compressionwill leak until the two o-rings 112 of the compression piston 106 arestraddling the inlet 114. This design prevents premature staple firing.

At the fully compressed position, the arm spreaders 110 are nearlyperpendicular to the longitudinal centerline of the stapler head. Oncetissue is compressed between cartridge 78 and anvil 96, the tissue isready for stapling.

Stapling is initiated by introducing hydraulic fluid through port 50 b(FIG. 5). The staple piston advances, pushing cutting element 86 (FIGS.7 and 10) towards the anvil 96. Because the staple pusher 76 is mountedto the cutter 86, this action carries the staple pusher 76 through thecartridge 78 where it simultaneously pushes all staples through thetissue. Staple piston travel is limited by internal stops, and is presetto yield optimal staple formation.

During compression, as the angle at the hinge 104 of arm assemblies 32reaches its minimum, the force required to resist separation of thestaple and anvil housings increases. These forces increase further whenthe forces of staple crushing are exerted on the anvil by the staplepiston. To compensate, the arm spreaders 110 serve as displacementstruts to channel at least a portion of these forces into the disk 68.These forces, if not reacted by the pusher disk, would pull in the arms100, 102 and potentially release the compression on the tissue, causingincomplete staple formation or tissue cutting. In this way, a truss-likestructure is created for force displacement.

When staples have been formed, staple pressure is released and a spring(not shown) returns the staple pusher 72 to its base position. Releasingfluid pressure will allow the deflected spring wires 46 on membraneraiser 37 to return the staple head to its minimum profile configurationand release the plication from the stapler. Once outside the patient,the used staple cartridge can be ejected and a new one installed.

FIGS. 25A-25C illustrate one method for retaining a removable staplecartridge 78 within the staple housing. The cartridge is spring-loadedinto the staple housing and retained by two latches 170 (one visible),each pivotable relative to a fulcrum 172. As shown, the fulcrum 172 maybe coupled to the disk 68 by pin 84. Each latch 170 includes a catch 174which engages a corresponding catch 176 on the cartridge. The latch 170is preferably spring biased to urge the catch 174 inwardly towards thecartridge.

Depressing the proximal end 175 of each latch 170 as shown by arrow P inFIG. 25B pivots the latch against this bias, causing ejection of thestaple cartridge. A new staple cartridge may then be positioned with itsgrooves 79 aligned with alignment posts 74 as shown in FIG. 25C and thenpushed towards the staple housing. As the new cartridge slides intoposition, catch 174 rides over the tapered proximal portion 178 of thecatch 176. Once catch 174 passes over the distal end 180 of the catch176, it drops inwardly towards the cartridge due to its spring bias,thus engaging the cartridge. When the cartridge is properly seated, aclick will be felt or heard as the latches engage the new cartridge.

Stapler Shaft and Handle

Referring again to FIG. 2, the stapler shaft 16 connecting the handle 18and the stapler head 14 is flexible enough to conform to the curvatureof the upper digestive tract, yet maintains the ability to transmitenough torque to rotate the stapler head. The shaft is formed withsufficient stiffness to allow it to be pushed down esophageal guide tube23. Suitable materials include

FIG. 26 shows a distal portion of the shaft 16, with the stapler headremoved from the shaft. As shown, shaft 16 includes an endoscope lumen124 through which an endoscope is advanced to allow visualization of astapling operation. Side lumens 126 may also be provided for receivingother instruments useful during the procedure.

An articulating section 128 is positioned at the distal end of the shaft16, between the shaft 16 and the stapler head 14 so as to allow thestapler head to be articulated relative to the shaft. Tubing coupled tothe vacuum source and the source of hydraulic fluid extends from thehandle and through the shaft 16 and the articulating section 128.

FIG. 27A shows one configuration that may be used for the hydraulicfluid lines 130. During use, the hydraulic fluid lines are subjected tosignificant deflection and elongation in the articulating section of thestapler. They are also subjected at times to fluid pressure which may bein excess of 1000 psi. Typically, hydraulic lines in industrialapplications are flexible and have a working loop of extra tubing thataccommodates length changes during use. The illustrated configurationfor the hydraulic lines is a lower profile solution particularlysuitable for an endoscopic device having space constraints. A preferredhydraulic line is a tube 130 having a portion that is shaped into alongitudinally expandable shape so that it can accommodate effectivelength changes during bending. The longitudinally expandable portion ofthe tube is preferably disposed within the articulating section 128 ofthe stapler 12. In a preferred design, the longitudinally expandableshape is a coil shape as shown in FIG. 27A. In alternate embodiments,the tube 130 may be formed into other longitudinally expandable shapes,such as regular or irregular undulating shapes (FIG. 27B).

The preferred material for the tubes 130 is stainless steel hypotube,although other materials may instead be used. In the preferred staplerconfiguration, two drive fluid lines are provided, one for actuatingtissue compression, and the other for staple application (and cuttingwhen used). In the present embodiment, the tubes are coiled together asshown in FIG. 27A. In alternate embodiments, two or more coiled tubesmay be nested one inside the other. As the articulating section bends,it forces the coiled tubes 130 to bend and to change length in responseto bending. The coiled tubes behave just as coiled wires would duringthese motions and are thus able to change length, deflect, and followthe contour of the articulating section without compromising flowthrough the lumens of the tubes or imparting undue stress to theconnections at either end of the hydraulic system.

The longitudinally expandable shapes for the fluid lines may be suitablefor use in allowing delivery of fluid to the operative ends of othertypes of articulating medical devices, such as catheters or endoscopicdevices for delivering therapeutic agents or irrigation fluids past anarticulating or bendable section of the device.

Referring again to FIG. 26, articulating section 128 is comprised of aspine formed of a plurality of links 132 strung over a pair of pullcables 134 (only one shown in FIG. 26). In one embodiment, engagement ofthe pull cables allows the stapler head 14 to be articulated in twodirections through a range of motion of approximately 90 degrees in onedirection (see FIG. 3B) to 175 degrees in the opposite direction (seeFIG. 3C). Each pull cable is anchored at or near the stapler head, suchas at the distalmost link 132 of the stapler housing 28.

The more proximal portions of the pull cables 134 extend the length ofthe shaft 16 and terminate in the handle 18. Referring to FIG. 28, thehandle 18 includes a rotating knob 136 that may be selectively rotatedin a clockwise or counterclockwise to articulate the stapler head up ordown. Rotation in one direction applies tension to one of the pullcables to cause the stapler head to bend downwardly, whereas rotation inthe opposite direction puts tension on the other cable, causing the headto bend upwardly.

In a preferred handle configuration, the knob 136 includes an internalthreaded bore 138. Knob 136 is partially restrained within the handle 18so that it remains fixed within the handle but can rotate freely. Acarriage 140 having a threaded exterior surface is positioned within thethreaded bore 128 of the knob. The threads within the bore 138 areengaged with the threads on the carriage 140 so that rotation of theknob causes the carriage 140 to translate, but not rotate, within thehandle.

Each of the two pull cables, identified in FIG. 28 as cables 134 a and134 b, is terminated on a different member in the handle. Cable 134 a ismounted on the sliding carriage and cable 134 b is mounted to astationary part of the handle 18. Each cable extends through acorresponding sheath. Cable 134 a extends through a sheath 135 a havinga proximal end fixed to a stationary part of the handle 18. Cable 134 bextends through a sheath 135 b having a proximal end mounted to thesliding carriage.

The cables 134 a,b and sheaths 135 a,b are arranged such thattranslation of the carriage in one direction will cause deflection ofthe stapler head in one direction, and translation of the carriage onthe other direction will deflect the stapler head in another direction.

Referring to FIG. 28, if knob 136 is rotated to causes the carriage 140to translate to the left of the page, cable 134 a will be tensioned andcable 134 b will slacken, causing the stapler head to articulate in afirst direction (e.g. upwardly). Rotation of the knob 136 in theopposite direction will advance the carriage to the right of the page,releasing tension on cable 134 a and pushing sheath 135 b over the cable134 b towards the distal end of the staple head, causing articulation inthe second direction (e.g. downwardly) as the sheath 135 b is advancedagainst a distal portion of the shaft 16. The proximal portion of sheath135 b is provided with sufficient working length prevent it from beingplaced under tension when the carriage moves distally. The positioningof the knob is advantageous in that the hand movement required forstapler articulation is always the same, regardless of the rotationalorientation of the stapler. Also, the use of the threaded knob canprevent unintentional relaxation of the deflection angle, even if theknob is provided without a lock to retain its rotational position.

Referring to FIGS. 28 and 29, the endoscope lumen 124 extends along thecenter axis of the stapler. The positioning of the lumen and the coaxialrelationship of the articulation knob in relative to the endoscope 124allows the endoscope and stapler to be rotated independently without oneinterfering with one another. Thus, if the user chooses to change therotational orientation of the stapler head 14 within the body, s/he mayrotate the handle 18 and shaft 16 while maintaining the rotationalposition of the endoscope.

For cost efficiency, the stapler 12 may be designed to permit thestapler head 14 to be discarded while allowing the shaft 16 and handle18 to be sterilized and re-used. One mechanism for removably couplingthe stapler head to the shaft 16 is illustrated, although others arereadily conceivable (e.g. a slip coupling type arrangement). Referringto FIG. 26, an end plate 142 is mounted to the distalmost one of thelinks 132. Each of the end plate 142 and the corresponding rear surfaceof the stapler head are provided with latch features that allow the endplate and stapler head to be engaged to one another.

End plate 142 includes a cantilevered pin 144 having a peg 145 (whichmay be a spring pin), a central opening 146, and a pair of u-shapedcatches 148 along its edges. Hydraulic feed holes 156 a, b are formedthrough the end plate 142. The hydraulic tubes that deliver hydraulicfluid to the stapler head (see tubes 130 of FIG. 27) are preferablywelded to the end plate to allow fluid from the tubes to be directedthrough the feed holes 156 a, b.

FIGS. 30A and 30B show the rear surface 48 a of the staple housing,which has been somewhat modified relative to FIG. 5. In this variationof the rear surface 48 a, the hydraulic input ports 50 a, 50 b arerepositioned as shown. Additionally, the rear surface 48 a has beenmodified to include a pair of catches in the form of undercut bosses150, plus an aligning pin 152, and a hole 154.

FIGS. 30A and 30B show the end plate 142 positioned against the rearsurface 48 a of the staple housing. The other features of thearticulating section 128 are not shown in FIGS. 30A and 30B for clarity.To attach the stapler head to the shaft 16, the plate 142, attached tothe handle assembly, is pressed against the rear surface 48 a of thestaple housing as shown in FIG. 30A. As the plate is pushed, it isrotated in a clockwise direction, causing the peg 145 (FIG. 26) of thecantilevered pin 144 to engage hole 154 in the rear surface of thestaple housing. When this latch is engaged, hydraulic feed holes 156 a,b of the end plate 142 are lined up with the hydraulic inlets 50 a, 50 bon the staple head as shown in FIG. 30B. At the same time, portions ofthe end plate surrounding u-shaped catches 148 slide beneath theundercut bosses 152. Pressing the plate compresses the face-sealingo-rings surrounding the hydraulic input ports 50 a, 50 b. Compression onthe o-rings is maintained by engagement of the catches and the undercutbosses overhanging the end plate. To remove the stapler head from thehousing, the stapler housing is twisted in a counterclockwise directionto disengage the end plate 142 from the rear surface 48 a. The staplershaft and handle may then be sterilized in preparation for mounting of afresh stapler head.

Exemplary Procedure

One example of a method for using the system 10 will next be describedin the context of formation of plications in stomach wall tissue.

As an initial step (FIG. 2), endoscopic guide tube 23 is advanced intothe stomach via the mouth and esophagus. The endoscope 22 is insertedinto the endoscope channel in the stapler handle (not shown) andadvanced down the lumen of the stapler handle. The stapler/endoscope aresimultaneously passed through the endoscopic guide tube towards thestomach. Once the stapler and endoscope reach the gastroesophagealjunction region of the stomach, the position of the stapler ismaintained while the endoscope is advance further into the stomach.

The stapler head 14 is advanced to the desired depth and location in thestomach. Using the articulation controls on the stapler handle, theangular orientation of the stapler head is adjusted to allow positioningof the stapler head 12 at the pre-identified target tissue as shown inFIG. 31A. The opening 26 in the membrane 24 is positioned against thetarget tissue. The endoscope 22 is placed in a retroflexed position asshown.

The vacuum source 20 (FIG. 2) is coupled to the vacuum port on thehandle external to the body, and vacuum pressure is applied to drawtissue through the opening 26 and into the vacuum chamber defined bymembrane 24 as shown in FIGS. 31B and 32A. Acquisition of the targettissue will be readily identified endscopically through the wall oftransparent membrane 24 on the stapler head.

The fluid source (is shown) is coupled to the handle. Once it has beenvisually confirmed that a sufficient amount of tissue has been acquired,fluid is introduced to cause compression of the tissue and expansion ofthe arm assemblies 32 and membrane raiser 37 as shown in FIGS. 32B and31C. As can been seen, the expansion of the arm assemblies and themembrane allows a large volume of tissue to be acquired into the vacuumchamber and displaced further into the chamber during tissuecompression.

Once the tissue has been compressed, additional hydraulic fluid isintroduced to cause stapling and cutting of the tissue as shown in FIGS.31D and 32C, forming a plication P. The compression and staplinghydraulic sources are then deactivated to release fluid pressure withinthe hydraulic circuit. With the hydraulic pressure relieved, the springwires of the membrane raiser 37 help to restore the stapler head 14 toits original streamlined configuration, allowing the stapler head to bewithdrawn from the tissue as shown in FIG. 31E. The stapler head may bearticulated relative to the shaft to assist in moving the stapler headaway from the plication P.

In a preferred plication configuration shown in FIG. 33 the staples 158are arranged in two concentric rings of five staples, with the staplereinforcement device 83 retained by the staples and distributing forcesaround the staple pattern as shown. The plication P includes a hole Hformed by the cutting element, through which various implants or anchorsfor various implants can be placed.

If multiple plications are needed, the stapler 12 is briefly withdrawnfrom the endoscopic guide tube and the staple cartridge is replaced inthe manner described in connection with FIGS. 25A-25C. The procedure isrepeated until all desired plications have been formed.

The system may be packaged with instructions for use instructing theuser to use the various disclosed features to perform a staplingprocedure using methods disclosed herein.

Alternate Embodiments

The basic architecture of the stapler disclosed above can be used as afoundation for other stapling tools. FIGS. 34-35 show a modified staplerin which the membrane and membrane raiser have been removed, and inwhich the staple housing 28 has been modified for the attachment oftools. As shown in FIG. 34, the staple housing 28 includes a pair ofgrooves 160 proportioned to receive tools 162. Tools 162 may be seatedin these grooves 160 and mounted to the staple housing as shown in FIG.35. This attachment will provide for a stable base from which to actuatethe tools. The tools may be self-articulating, or the staple housing 28may be equipped with devices 164 for moving the tools betweenstreamlined positions for insertion of the assembly into a body cavity,and a deployed position such as that shown in FIG. 35. Tools similar tothose in FIG. 35 might be used for tissue acquisition, by reachingbetween the cartridge and anvil and used to engage tissue and pull thetissue into position between the cartridge and anvil so that it may bestapled, or otherwise affected by various features added to or in placeof the anvil and cartridge. Procedures which may benefit from adaptationof the stapler include, but are not limited to gastroplasty, stomaadjustment, polyectomy, lead placement, bleeding control, perforation orhole closure, biopsy and tumor removal.

The disclosed systems provide convenient embodiments for carrying outthe disclosed compression and stapling functions. However, there aremany other widely varying instruments or systems may alternatively beused within the scope of the present invention. Moreover, features ofthe disclosed embodiments may be combined with one another and withother features in varying ways to produce additional embodiments. Thus,the embodiments described herein should be treated as representativeexamples of systems useful for forming endoscopic tissue plications, andshould not be used to limit the scope of the claimed invention.

Any and all patents, patent applications and printed publicationsreferred to above, including those relied upon for purposes of priority,are incorporated herein by reference.

1-87. (canceled)
 88. A medical instrument for applying a fastener totissue, comprising: a head including: a first member carrying at leastone fastener; a second member, the first and second members relativelymoveable towards one another into a tissue compressing position; and afiring element advanceable to drive the fastener from the first membertowards the second member using a driving force, the driving forcesufficient to produce separating forces against the first and secondmembers; and a force displacement strut positioned to displace a portionof the separating forces to resist displacement of the first and secondmembers from the tissue compressing position by the driving force. 89.The medical instrument according to claim 88, wherein the forcedisplacement strut has a longitudinal axis transverse to a direction ofthe separating forces.
 90. The medical instrument according to claim 88,wherein the head includes; an arm assembly having a first sectionpivotally coupled to the first contact member and a second sectionpivotally coupled to the first section and the second member; andwherein the force displacement strut extends between the arm assemblyand either the first member or the second member.
 91. The medicalinstrument according to claim 90, wherein the force displacement strutextends between the first section and the first member.
 92. The medicalinstrument according to claim 88, wherein: the first member includes afastener holder moveable relative to the first member towards the secondmember; the head includes an arm assembly having a first sectionpivotally coupled to the first member and a second section pivotallycoupled to the first section and the second member; and the forcedisplacement strut extends between the first section and a portion ofthe fastener holder.
 93. The medical instrument according to claim 92,wherein: the fastener holder includes a drive member moveable on thefirst member from a first position to a second position to move thefastener holder towards the second member; and the force displacementstrut has a first end pivotally coupled to the first section and asecond end pivotally coupled to the drive member.
 94. The medicalinstrument according to claim 93, wherein the force displacement strutis pivotable from a first orientation to a second orientation inresponse to movement of the drive member from the first position to thesecond position.
 95. The medical instrument according to claim 94,wherein the arm assembly is pivotable away from the head from a firstposition in which the first member and second member housing areseparated by a first distance, and a second position in which the firstmember and second member are separated by a second, smaller distance.96. The medical instrument according to claim 95, wherein the forcedisplacement strut is positioned such that movement of the forcedisplacement strut to the second orientation moves the arm assembly tothe second position.
 97. The medical instrument according to claim 88,wherein the at least one fastener is carried by a fastener holder, thefastener holder comprising a cartridge removably coupled to the firstmember.
 98. The medical instrument according to claim 88, wherein themedical instrument is a medical stapler, wherein the first membercomprises a staple housing including a staple holder carrying at leastone staple, and wherein the second member comprises an anvil supportincluding an anvil.
 99. The medical instrument according to claim 98wherein the head includes an arm assembly having a first sectionpivotally coupled to the staple housing, and a second section pivotallycoupled to the first section and the anvil support; and the forcedisplacement strut extends between the first section and the staplehousing.
 100. The medical instrument according to claim 99, wherein thestaple holder includes a drive member moveable on the staple housingfrom a first position to a second position to move the staple holderrelative to the staple housing towards the anvil; and the forcedisplacement strut has a first end pivotally coupled to the firstsection and a second end pivotally coupled to the drive member.
 101. Amethod of applying a fastener to a workpiece, the method comprising:positioning a workpiece to be fastened between a first member and asecond member; moving the first and second members relatively towardsone another into a compression position to compress the workpiecebetween them, the first and second members in the compression positionseparated by a gap having a width; driving at least one fastener fromthe first member into the workpiece, wherein driving the fastener intothe workpiece generates separating forces against the first and secondmembers; and displacing at least a portion of the separating forcesalong a displacement strut to thereby maintain the width of the gap.102. The method of claim 101, wherein: the method includes providing ahead including the first and second members and at least one armextending between the first and second members, the arm including afirst section pivotally coupled to the first member and a second sectionpivotally coupled to the first section and the second member, the forcedisplacement strut extending between the arm and the first or secondmember. positioning the first member and second member in thecompression position includes causing the arm to pivot to form an anglebetween the first and second members; and the separating forcesincluding angular forces oriented to increase the angle; and displacingthe separating forces includes displacing the angular forces along thedisplacement strut so as to substantially maintain the angle.
 103. Themethod according to claim 102, wherein: providing the head includesproviding a fastener holder on the first member, the fastener holdercarrying the at least one fastener and being coupled to a drive member,the force displacement strut having a first end pivotally coupled to thearm and a second end pivotally coupled to the drive member; andpositioning the first member and second member includes advancing thedrive member to move the fastener holder relative to the first member ina direction towards the second member, wherein advancing the drivemember pivots the force displacement strut to a laterally extendingposition.
 104. The method according to claim 103, wherein pivoting theforce displacement strut to the laterally extending position causes thearm to pivot at the hinge to form the angle.
 105. The method accordingto claim 102, wherein the method provides the at least one fastener tobe carried by a fastener cartridge removably attached to the firstmember.
 106. The method according to claim 101 wherein the method is amethod for applying a fastener to tissue, and wherein positioning aworkpiece includes positioning tissue to be fastened between the firstand second members.
 107. The method according to claim 101, wherein themethod is a method for applying a staple to tissue, and wherein:positioning the workpiece between the first and second members includespositioning the workpiece between a staple housing and an anvil; movingthe first and second members into the compression position includesmoving the anvil and staple housing relatively towards one another. 108.The method according to claim 107, wherein driving the at least onefastener includes advancing a staple driver at least partially through astaple holder carrying at least one staple. 109-242. (canceled)